The concept of shut-off valves that automatically shut off the flow of fluid through a fluid line in response to a fault condition are known in the art. Typically, such shut-off valves are made from multiple parts and are quite complex. The present invention provides for a one-piece shut-off valve that can be molded in one operation to produce a low cost shut-off valve that can be used in irrigation systems to shut off the flow of water should a sprinkler head get damaged.